Method of making spark plugs



Jan. 5; 1943. E. HAAS METHQD OF MAKING SPARK PLUGS Filed Nov. 2, 1940 Patented Jan. 5, 1943 UNETED STATE 'i'i QFFHCE.

METHOD OF MAKING SPARK PLUGS Edward Haas, Brooklyn, N. r.

Application November 2, 1940, Serial No. 363,991

5 Claims.

This invention relates to improvements in spark plugs and more particularly to improvements in spark plugs of the type in which substantially the entiresparking zone is located within the shell of the plug, and also to improvements in making the same.

An object of the present invention is to provide a spark plug so constructed that the center electrode and the ground or shell electrode have flats on the side walls thereof which flats are so located as to be in substantial parallelism and substantially completely within the shell.

Another object of the invention is to provide a spark plug having the sparking surfaces of the electrodes thereof of substantially fiat nature ar-' ranged within the shell of the plug in substantial parallelism along chords of the shell.

Another object of the invention is to provide new, simple and eflicient methods of constructing a spark plug of the foregoing character.

A further object of the invention is to provide a method of constructing a spark plug as defined above in which method a flat is provided on the center electrode while such center electrode is firmly locked in the shell of the plug.

Other features, objects and advantages of the invention will become apparent by reference to the following detailed description of the accompanying drawing wherein Fig. l is a fragmentary side elevation of one end of a spark plug shell showing a ground or shell electrode attached thereto and illustrating diagrammatically the manner in which a fiat can be formed on one or two sides of the electrode;

Fig. 2 is a view similar to Fig. 1 showing the same organization afterfiats have been provided on the ground or shell electrode;

Fig. 3 is an end view illustrating diagrammatically the manner in which a, flat can be formed on the center electrode while this electrode is held in firm assembly with the shell;

Fig. i is an end view of the same assembly subsequent to the formation of a fiat on the center electrode;

Fig. 5 is a similar view of the same parts after the ground or shell electrode has been bent down into sparking relation to the center electrode;

Fig. 6 is a side elevation on a complete plug embodying the invention, such plug being shown with parts thereof broken away to illustrate the relative positions of the electrodes, and

Fig. '7 is a diagrammatic representation of a modification for forming flats on both of the electrodes simultaneously.

Referring now to thedrawing and particu- 55 larly to Figs. 1 to 6 inclusive, Ill indicates generally the shell of a spark plug which has a reduced neck portion H, externally threaded. A center electrode l2 of suitable metal is held in assembly with the shell by means of an insulating sleeve I l of suitable material, such as porcelain or other ceramic material, and a bushing l 5 threaded into one end of the shell all in a conventional fashion. In addition, the spark plug has a ground or shell electrode 56 of suitable metal staked or otherwise secured in the shell neck I i and designed to cooperate with the center electrode l2. It will be observed by study of Fig. 6 that substantially all of the lower end of the electrode I 2 extending beyond the insulator sleeve lilies within the shell 51 and that the free end of the ground electrode I6 is bent downwardly so that the part of this electrode opposite the center electrode likewise lies substantially completely within the shell.

In manufacture of plugs it is impractical to provide a flat on one end of the center electrode and then to lock such flat at any desired position within the shell, since the process of locking the electrode in the shell by tightening the bushing 5 5 precludes such location. Likewise it is impractical by methods known to applicant to provide flats on both electrodes after these electrodes have been locked in their normal sparking relation. Accordingly, the present invention provides two methods of constructing spark plugs having flats extending longitudinally of the electrodes with opposite sparking areas of the two electrodes located substantially entirely within the shell.

In Fig. 1 the neck H of the shell has again been illustrated and the ground or shell electrode 46 is shown extending directly outwardly from the end of the shell. Flats can be provided in diametric opposite disposition on the length of the electrode by application of force through the agency of two forming members 29 and El, one of which can be a stationary member or both of which may be made movable. As a result of ap plication of pressure or force through the agency of members 2!; and 2|, flats 22 and 2 3 are provided on opposite sides of the electrode it as shown in Fig. 2. The flat 22 is the essential flat in this construction and it is so located as to lie along a chord of the shell H. The fiat 24 is merely incidental to the production of fiat 22 and it can be eliminated if desired by shaping the member 2!) in such fashion as to preserve the original roundness of that part of the electrode contacting the member 20.

As the next step in the manufacture of this plug the center electrode i2 is locked in assembly with the shell H and then a flat is provided on a side of the electrode l2 through the agency of two members 25 and 25. The member 26 has its end surface hollowed out into round form as at 2'! to conform to the shape of the electrode l2. The member 25, on the other hand, has a square end 28 so that when force is applied by the member 25 to the electrode i2, which in turn is supported by the member 26, the result of such force is the formation of a flat 29 (Fig a) on the electrode I2. The parts during this operation are so aligned that the flat 29 lies along a chord of the shell H in substantial parallelism to the fiat 22 on the electrode i5 but in spaced relation to this flat 22.

As the final step in the manufacture of the plug, the electrode I6 can be bent inwardly with the flat 22 maintained on its chord so that the parallel relation between flats 22 and 29 can be preserved. The respective chords of these two flats are normally predetermined in such fashion that the electrodes will, in the finished article, be spaced apart the desired amount depending upon the intended characteristics of the plug. For example, if desired, the flats 22 and 28 can be spaced apart a distance of m of an inch or any other suitable distance depending upon the use for which the plug is designed.

The finished plug has opposing surfaces of its electrodes of maximum width to obtain maximum sparking areas so that frequent adjustment or spacing of the electrodes is not required even after long continued use of the plug. Furthermore, since substantially the entire sparking zone of the plug is located within the shell thereof, it follows that radiation of heat from the sparking zone can be accomplished with great efliciency.

As a modification of the method of manufacture, it is contemplated that the plug can be produced in the manner shown in Fig. '7 wherein it will be seen that an assembly of shell center electrode and ground electrode is processed to provide flats on the two electrodes simultaneously. In this modification the shell Ii has locked thereto a center electrode I2 and has staked or otherwise secured thereto a ground or shell electrode i6. Forming members 29' and 2! may be so correlated with forming members 25' and 26 that by one operation carried out simultaneously with these correlated parts, a flat 29' is formed on the center electrode and a flat 22' on the ground electrode. Again the opposite flat on this latter electrode is merely incidental and is not essential in the construction.

While the present invention has been illustrated in connection with a plug having a central electrode and a single shell or ground electrode, it would be apparent that two or more shell or ground electrodes can be employed if desired and that the invention adapts itself to such construction.

From the foregoing it will be seen that the present invention provides a new, improved and highly efficient spark plug together with novel methods of making the same. It is to be understood that modifications both in the plug and in the methods of making the same can be accomplished without departing from the spirit and scope of the invention which is to be determined only by the following claims.

What is claimed is:

1. The method of constructing a spark plug having a central electrode, the end of which is substantially entirely within the shell and a shell electrode which comprises forming longitudinally extending flats on the sides of the two electrodes, and bending the shell electrode into position in which it extends across the shell with the flat thereon lying along a chord of the shell spaced from the flat on the center electrode in substantial parallelism therewith.

2. The method of constructing a spark plug having a central electrode substantially entirely within the shell and a shell electrode which comprises pressing a longitudinally extending flat on the side of the shell electrode while it extends longitudinally from the shell, locking the central electrode in assembly with the shell, pressing a longitudinally extending fiat on the side of the central electrode in substantial parallelism with the flat on the shell electrode, and bending the shell electrode into position in which it extends across the shell along a chord spaced from and substantially parallel to a diameter of the shell and the flat thereon is spaced from the flat on the central electrode.

3. The method of constructing a spark plug which comprises securing a central electrode in a shell in insulated relation thereto, said shell having a shell electrode extending longitudinally therefrom, simultaneously forming flats on the sides of the central electrode and the shell electrode with such flats in substantial parallelism, and bending the shell electrode into a position in which it extends across the shell along a chord spaced from and substantially parallel to a diameter of the shell and the fiat thereon is adjacent to but spaced from the flat on the central electrode.

4. The method of constructing a spark plug which comprises securing a central electrode in a shell in insulated relation thereto with the end of the electrode substantially entirely within the shell, simultaneously pressing flats on the sides of the central electrode and of a shell electrode extending longitudinally from the shell with such flats in substantial parallelism, and bending the shell electrode into a position in which it extends across the shell along a chord spaced from and substantially parallel to a diameter of the shell and the flat thereon is adjacent to but spaced from the flat on the central electrode.

5. The method of constructing a spark plug which comprises securing a shell electrode to the shell to extend longitudinally therefrom, securing a central electrode in the shell in insulated relation thereto and with the end of the electrode substantially entirely within the shell, simulta neously pressing flats on the sides of the central electrode and the shell electrode with such flats in substantial parallelism along chords of the shell, and bending the shell electrode into a position in which it extends across the shell along a chord spaced from and substantially parallel to a diameter of the shell and the flat thereon is adjacent to but spaced from the fiat on the central electrode.

EDWARD HAAS. 

